Jib cranes



March 41958 H. L. Busi-:MAN

JIB'CRANES Filed June 22, 195s United States Patent Qg JIB CRANES Howard L. Bushman, Wayne, Ill.

Application June 22, 1953, Serial No. 363,203

2 Claims. (Cl. 212-28) This invention relates to jib cranes, and particularly to the way in which the rotatable jib is mounted on the supporting standard or column of such a crane.

Jib cranes have, of course, been constructed in many different ways, but one of the most common arrangements has included a column made from a relatively large cylindrical pipe, with the jib rotatably supported on the upper end of the column by means including laterally acting anti-friction rollers which roll upon the outer surface of the cylindrical column. In such prior structures, it has been found that the attainment of a proper rolling relationship of the anti-friction rollers upon the surfaces of the cylindrical column has been extremely difficult to at- Y tain, and this has been due, at least in part, to the fact that the columns are not in every instance produced with true cylindrical outer surfaces, and it has also been due to the fact that inaccuracies of original manufacture or inaccuracies due to progressive wear of the parts have caused the anti-friction bearings to engage the column along lines at edge contact rather than with a true and complete rolling engagement. It is, therefore, an important object of the present invention to simplify and improve the construction of jib cranes so that a proper application of the load-imposed forces between the column and the jib may be attained in every instance, and a related object is to attain this result in a simple and inexpensive manner.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and what I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is an elevational view of a jib crane embodying the features of the invention;

Fig. 2 is a fragmentary plan View of the crane;

Fig. 3 is an enlarged cross sectional view taken along the line 3-3 of Fig. 1;

Pig. 4 is a fragmental view taken in vertical section along the line 4-4 of Fig. 3; and

Fig. 5 is a side elevational view of one of the beating carriers.

For purposes of disclosure, the invention is herein illustrated as embodied in a jib crane 10 having an upstanding column 11 formed from a cylindrical pipe, and having a mounting base 12 formed from a iiat base plate 13 that is joined to the lower end faces of the column 11 by welding, and which is braced with respect to the column by means of angular gusset plates 14 that are disposed between the base plate 13 and the column 11 in plates passing through the axis of the column and located at 2,825,47l Patented Mar. 4, 1958 2 equally spaced intervals about the axis of the column. The base plate 13 is adapted to be secured to theroor or any other mounting surface by means such as anchoring bolts 15 that are passed downwardly through appropriate openings 13A formed in the base plate 13.

At its upper end, the column 11 is arranged to rotatably support a projecting jib v20`which is, in the presentv instance, arranged in a horizontal position. The jib 20 as herein shown is formed by an I beam that has upper and lower flanges 20U and 20L, and an intermediate connecting web 20W that is located in a vertical plane. At the inner end of the jib 20, means are afforded for supporting the jib on the top of the column 11, and, as herein shown, such means comprise a pair of gusset or side plates 21 that are disposed along opposite edges of the webs 20U and 20L in an opposed or symmetrical relationship, and are welded or otherwise securely xed to these flanges 20U and 20L. The gusset or side plates 21 extend downwardly along opposite sides of the column 11 in a parallel relation to the axis of the column and to each other, and the lower flange of the jib 20 is disposed directly over and in parallel relation to the upper end of the column 11. The vertical forces between the jib and the column are, in the present instance, arranged to be taken by means such as a ball thrust bearing 22 that may be appropriately secured in position with these parts in accordance with common practice.

The gusset or side plates 21 serve as a mounting means for bearings that absorb the other forces applied to the jib 20, and such bearing means, in accordance with the present invention, comprise an upper roller bearing unit 25U and a lower bearing unit 25L which are of identical position and which differ only in their specic location between the two side plates 21.

The bearing units 25L and 25U each comprise a rocking carrier 26 having parallel top and bottom walls 26U and 26L connected rigidly in spaced relation by end walls 26E. The end walls 26E are spaced apart in such a dimension that the carrier 26 will lit loosely betweenfthe side plates 21, as shown in Pig. 3, and the carrier is mounted in this position by a mounting bolt 27 that extends through the two side plates 21 and the end walls 26E. Between the horizontal walls 26U and 26L of the carrier 26, a pair of rollers 28 are rotatably mounted on vertical axes by mounting pins 29, and these rollers 28 are symmetrically located with respect to the ends of the carrier 26 so that they may bear against the column 11 in a symmetrical relation with respect to a vertical plane passing through the horizontal axis of the jib 20 and the vertical axis of the column 11. The edges of the horizontal walls 26U and 26L that are adjacent the rollers 2S are cut away arcuately as at 26C, Fig. 3, for clearance purposes. The rollers 28 may bear with a true rolling action by reason of the self adjusting action that is provided by the pivotal mounting of the carrier 26 on the bolt 27. The maximum range of automatic pivotal adjusting or conforming movement of the carriers 26 that is required is, of course, relatively small, and hence I prefer to alford limit stops 30 on the inner faces of the side plates 21 for engagement by the upper and lower edges of the carrier 26, as shown particularly in Figs. 3 and 4 of the drawing.

By reason of the improved bearing mounting that is thus afforded under the present invention, it has been found that lack of uniformity of dimension and circularity of the columns 11 becomes an unimportant consideration in the manufacturing operations involved, and the mounting of the bearing rollers is materially simplified and rendered more economical. Moreover, the wearing characteristics of the structure are so improved as to minimize wear and insure proper and effective operation of the crane.

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